Blocking oscillator having selectively adjustable r-c circuit



H. BURGER July 18, 1961 BLOCKING OSCILLATOR HAVING SELECTIVELY ADJUSTABLE R-C CIRCUIT Filed March 5, 1956 jm/d $2736)":

' 2,993,178 BLOCKING OSCILLATOR VlNG SELECTIVELY ADJUSTABLE R-C CIRCUIT Harald Burger, Erlangen, Germany, assignor to Siemens- Reiniger-Werke Aktiengesellschaft, Erlangen, Germany, a firm Filed Mar. 5, 1956, Ser. No. 569,324 Claims priority, application Germany Mar. 11, 1955 2 Claims. (Cl. 331146) This invention relates to an electric high-frequency surgical apparatus having a tube oscillator for producing electric oscillations of high frequency.

Previously known high-frequency surgical apparatuses of this type comprise a-sel-f-eXcited tube generator producing undamped high-frequency oscillations. The highfrequency currents of such a generator are well adapted to sever parts of the tissue by cutting, using a cutting electrode, for instance a Wire loop or snare. However, for coagulation such high-frequency currents are less suitable. Therefore, especially in the resection of the prostate by electro-surgical means Where it is additionally required alternately to cut and to coagulate by means of one and the same electrode, and mostly by a wire loop, as a rule high-frequency surgical apparatus fitted with spark gap generators are used. Such spark gap type surgical apparatus operate with damped high-frequency oscillations, that is, high-frequency oscillations the amplitude of which decreases periodically within a short period from a high initial value to zero. Such apparatus, however,'have decidedly poorer cutting characteristics United States PatentQ ice than surgical apparatus operating with tubes, and morequency generators, are relatively expensive, heavy and V bulky.

It is an object of the present invention to provide an apparatus adapted to carry out coagulating and cutting operations with a single high-frequency generator, that is, with a tube generator.

With this and further objects in view, the present invention is based on recognition of the fact that a blocking oscillator-that is, a feed-back or regenerative oscillator in which the combination of resistances and condenser means inserted in the control grid circuit of the generator tube are so selected that the value of the potential at the control grid changes periodically up to such a high negative value that this potential impedes the flow of current through the valve to produce oscillations of high frequency which, similar to high-frequency oscillations produced by spark gap generators, start periodically with a large amplitude and then decrease quickly in amplitude down to zero, and by a change of only the time constants of its resistance-condenser combination in the control grid circuit conversion may be effected into a self-excited valve generator for the production of undamped oscillations.

Therefore, according to the invention in an apparatus for high-frequency surgery comprising a tube generator for producing the electric oscillations of high frequency, a blocking oscillator is used as a tube generator which contains in its control grid circuit a resistance-condenser combination the time constant of which can be brought to such low values, by the operation of switching means, that the above mentioned periodical decrease of the am- 2,993,178 Patented July 18, 1961 plitude of oscillations is prevented, thus permitting the generation of continuous high-frequency oscillations of constant amplitude. This change of the time constants can be effectedfor instance by disconnecting a capacity normally connected in parallel to the capacity of the resistance-condenser member of the grid circuit. Such a disconnection can be elfected by means of a relay which is connectible and disconnectible through a manual switch arranged on the handle for the surgical electrode, or by means of a foot pedal switch.

Since as a rule the output required for coagulating is difierent from that required for cutting it is necessary, in case of alternating coagulating and cutting operations, to manually readjust the regulator for the output each time the resistance-condenser 'member is switched over from (:utting" to coagulating or vice versa. According to aprefer'red form of the invention, such an additional- 1y required manual readjustment of the regulator for the output is achieved in such a way that the relay effecting the change of the resistance-condenser member also effects the required change of the regulator for the output. Advantageously separate regulators are provided for controlling the output during coagulating operations and for controlling the output during cutting operationsan'd' the relay acts to change over from one of the two regulators to the other.

Other and further objects, features and advantages of the. invention Will be pointed out hereinafter and appear in the appended claims forming part of the application.

The accompanying drawing shows an example of a now preferred embodiment of the invention.

FIG'.'-l is a circuit diagram of an apparatus embodying the present invention;

FIG. 2 is an oscillogram showing the amplitude of the high-frequency oscillations produced, plotted against time, when the apparatus is adjusted for cutting operations;fand j V 'FIG. 3 is a similar view but showing the amplitude of the Oscillations when the apparatus is adjusted for coagulating operations.

Referring tof-FIG. 1, there are provided a generator D and apower'amplifier E respectively delimited by dot and dashlines. The generator D comprises a three electrode tube or triode V including a cathode K a control grid G and an anode A The filament of the tube V is indicated by F and its source of current by B The cathode K is connected to the negative pole of the source of anode current B and grounded. The anode A is connected with a resonance circuit comprising a coil L disposed in parallel with a capacity C and by way of a switch (not shown) with the positive pole of the source of anode current B The control grid G is connected to the coil L which is coupled to the coil L The free end of the coil L is connected to the connecting point between the series-connected resistance R and condenser C of a resistance-condenser combination; the free end of the resistance R is connected to the positive pole of the source of anode current B while the free terminal of the condense'rC is grounded. One end of the coil L which is coupled with the coils L and L is grounded while the other end is connected to otentiometers R and R the 7 other ends'of which are grounded. As will be presently grid amplifier tube V the cathode K of which is grounded and the filament F;, of which is powered by a heating battery B The control grid G of the tube V is connected, through a protective resistance R, and a choke L4, with the negative pole of a source of grid voltage B3 the-positive pole of which is grounded and which is bridged by a condenser C Connected to the connecting point between the choke L andthe protective re-- sistance R is a coupling condenser C to which the voltages which can be taken from the slides R or R can be applied, as Will be presently described. The screen grid G of the tube V is connected on the one hand, through a resistance R with the positive pole of the source of voltage B and on the other hand, through a condenser C it is grounded-with regard to high he quency. The anode A of the tube V is connected to the positive pole of the source of anode voltage B over an inductance coil L shunted by a condenser C7, and by way of a switch (not shown). The negative pole of the source of anode voltage B is grounded and bridged by a condenser C The inductance L and the capacity C7 shunted thereto form a resonance circuit for the electric high-frequency oscillations produced by the generator D, Coupled withthe coil L is a coil L one end is grounded while its other end is connected by way of an isolating condenser C with a surgical cutting instrument K which is attached to a handle I to be held by the surgeon. The object to be treated is indicated by O and lies on a metallic base T which isgrounded.

In order to change the method of operation of the apparatus and to produce a high-frequency current adapted for coagulations or for cutting, as occasion demands, there is provided a relay A the coil of which is connected with one of its terminals to the positive pole of the voltage source B while its other terminal is connected, by push-button switches F and H which are pedaloperated and hand-operated, respectively, with the negative pole of the voltage source B that is, grounded. The manually operated switch H may also be accommodated in the handle I of the cutting instrument K as indicated by the dotted line W. The relay has an operating or make contact a, and a make-break contactfsystem a;. The make contact a is inserted in the connection of one way of the inductance L to the surgical instrument K. .The amplitude of the current thus produced and being particularly adapted for cutting is plotted against time in the oscillogram shown in FIG. 2. I i

If it is intended to obtain from the output circuit of the apparatus a current adapted for coagulation, either the pedal switch F or the manual switch H is depressed so as to-eifect energization of the relay A. Make contact a is thereby actuated to connect the condenser C having a relatively large capacity, in parallel to the condenser C Moreover; the slide R of the potentiometer R is connected with the condenser C of the amplifier circuit'E through the lead Y, the make side a of the make-break contact a and the lead X. By. the parallel connection of the capacity C with the capacity C the efiective total capacity is increased. Hence, the current fiowing across the grid-cathode space of the tube V is eifective to change the charge of this capacity in such a way that an increasing negative potential is produced on the control grid G of the tube V causing the anode current to drop to zero. The generation of oscillations is thus stopped until the charge of the condenser combination C C is changed to such an extent, through the resistance R that a positive bias is again applied to the control grid G of the tube V Damped high-frequency oscillations quickly decreasside of the condenser C and the connecting point he tween the resistance R and one side of the condenser C the other side of which is grounded. The pivot side a of the make-break contact a is connected with the condenser C by way of conductor X. The normally closed side a of the make-break contact a is. connected through a line Zwith the slide R of the potentiometer R 2 The make side a of the make-break contact a is connected through a lead Y with the slide R of the potentiorneter R 7 g t The operation of the circuit arrangement isas follows If the tubes V and V are connected, by means of the switch which is not shown, to their sources of current B B B and B a positive bias is'applied to the control grid G of the tube V in case of open push-button switches P and H, said bias being derived from the series connection of the resistance R and the capacity C The side of the condenser C connected to thegrid side of the tube is positively charged, while the cathode side is negatively charged. The positive grid bias permits the production of undamped oscillations or continuous waves through the circuit D. In an oscillating state of this circuit, a current tending to change the charge of condenser C in such a way that a positive charge is built up on the cathode side and a negative charge is built up on the grid side, flows from the controlgrid G across the grid-cathode space of the tube V to the cathode K This recharging voltage, however, in view of the small capacity of the condenser C is low compared to 'the positive charging voltage applied through the resistance R from the positive pole of the voltage source B The grid side of the condenser C therefore remains at a positive potential. Through the coil L undamped continuous high-frequency oscillations are attenuated and applied to the potentiometers R and R Through the slide R of the potentiometer R the lead Z, the normally closed side a of the make b1jeak contact a and ing in amplitude and being adapted for coagulation are thus periodically produced in the output circuit of the amplifier with the tube V the characteristic of these oscillations being indicated in FIG. 3.

The output of the undamped high frequency currents adapted for cutting is controlled by the potentiometer R while the output of the discontinuousdamped high frequency currents adapted for coagulation is controlled by the potentiometer R The variable or control-resistances R2 and R are adjustable in such a way that the desired value of the output of the apparatus is always available for coagulation or cutting operation.

Changes may be made within the scope and spirit of the appended claims which define what is believed to be new and desired to have protected by Letters Patent.

- I claim: i i

1. In a high frequency surgical apparatus having a surgical instrument for alternately performing coagulating and tissue-cutting operations, a self-excited tube generator comprising a blocking oscillator including a control grid circuit and having circuit means forming an output circuit for oscillations produced thereby, resist ance-capac-itor combination means for governing said control grid circuit, first switching means adapted in one switching position to selectively adjust the time constant of said resistance-capacitor combination means to such a high value that first distinct high frequency output oscillations are periodically produced and then rapidly reduced to a minimum, and in another switching position adapted to selectively adjust the time constant of said resistancecapacitor combination means to such a low value that second distinct and continuous high frequency output oscillations are produced, second switching means for selectively connecting said first and second distinct output oscillations to energize said surgical instrumentso as to adapt it to alternately perform the respective coagulating and cutting operations, control means connected to said,

lating and tissue-cutting operations, a self-excited tube generator comprising a blocking oscillator including a control grid circuit and having circuit means forming an output circuit for oscillations produced thereby, resistance-capacitor combination means for governing said control grid circuit, first switching means adapted in one switching position to selectively adjust the time constant of said resistancecapacitor combination means to such a high value that first distinct high frequency output oscillations are periodically produced and then rapidly reduced to a minimum, and in another switching position adapted to selectively adjust the time constant of said resistance-capacitor combination means to such a low value that second distinct and continuous high frequency output oscillations are produced, second switching means for selectively connecting said first and second distinct output oscillations to energize said surgical instrument so as to adapt it to alternately perform the respective coagulating and cutting operations, control means connected to said output circuit for selectively respectively governing the magnitude of said first and second output oscillations,

relay means comprising contacts constituting respectively said first and second switching means, a break-make contact constituting said second switching means, circuit means for interconnecting said make-break contact with the respective control means for connecting the respective output oscillations to energize said surgical instrument alternately in accordance therewith, and a switch for controlling the actuation of said relay means.

References Cited in the file of this patent UNITED STATES PATENTS 1,621,034 Slepian Mar. 15, 1927 1,632,054 Brown June 14, 1927 1,695,485 Fayer Dec. 18, 1928 1,724,508 Nauth Aug. 13, 1929 2,396,439 Schlesinger Mar. 12, 1946 2,593,501 Thomas Apr. 22, 1952 2,611,365 Rubens Sept. 23, 1952 2,622,200 Hodgson Dec. 16, 1952 

